linux-kernel - Re: [PATCH net-next v3 19/19] net: ravb: Add runtime PM support

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Date: Tue, 9 Jan 2024 22:53:48 +0300
From: Sergey Shtylyov <s.shtylyov@....ru>
To: Claudiu <claudiu.beznea@...on.dev>, <davem@...emloft.net>,
	<edumazet@...gle.com>, <kuba@...nel.org>, <pabeni@...hat.com>,
	<richardcochran@...il.com>, <p.zabel@...gutronix.de>,
	<yoshihiro.shimoda.uh@...esas.com>, <wsa+renesas@...g-engineering.com>
CC: <netdev@...r.kernel.org>, <linux-renesas-soc@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <geert+renesas@...der.be>, Claudiu Beznea
	<claudiu.beznea.uj@...renesas.com>
Subject: Re: [PATCH net-next v3 19/19] net: ravb: Add runtime PM support

On 1/5/24 11:23 AM, Claudiu wrote:

> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> 
> Add runtime PM support for the ravb driver. As the driver is used by
> different IP variants, with different behaviors, to be able to have the
> runtime PM support available for all devices, the preparatory commits
> moved all the resources parsing and allocations in the driver's probe
> function and kept the settings for ravb_open(). This is due to the fact
> that on some IP variants-platforms tuples disabling/enabling the clocks
> will switch the IP to the reset operation mode where registers' content is
> lost and reconfiguration needs to be done. For this the rabv_open()
> function enables the clocks, switches the IP to configuration mode, applies
> all the registers settings and switches the IP to the operational mode. At
> the end of ravb_open() IP is ready to send/receive data.
> 
> In ravb_close() necessary reverts are done (compared with ravb_open()), the
> IP is switched to reset mode and clocks are disabled.
> 
> The ethtool APIs or IOCTLs that might execute while the interface is down
> are either cached (and applied in ravb_open()) or rejected (as at that time
> the IP is in reset mode). Keeping the IP in the reset mode also increases
> the power saved (according to the hardware manual).
> 
> Reviewed-by: Sergey Shtylyov <s.shtylyov@....ru>
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
[...]

> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
> index e909960fbc30..e99351fe8d7f 100644
> --- a/drivers/net/ethernet/renesas/ravb_main.c
> +++ b/drivers/net/ethernet/renesas/ravb_main.c
[...]
> @@ -2233,7 +2243,14 @@ static int ravb_close(struct net_device *ndev)
>  	ravb_get_stats(ndev);
>  
>  	/* Set reset mode. */
> -	return ravb_set_opmode(ndev, CCC_OPC_RESET);
> +	error = ravb_set_opmode(ndev, CCC_OPC_RESET);
> +	if (error)
> +		return error;
> +
> +	pm_runtime_mark_last_busy(dev);
> +	pm_runtime_put_autosuspend(dev);

   BTW, doesn't make sense to check/return the result?

> +
> +	return 0;
>  }
>  
>  static int ravb_hwtstamp_get(struct net_device *ndev, struct ifreq *req)
[...]

MBR, Sergey